Cost for a cottage addition on concrete piers?

Hello,

I am just wondering what the estimated price per square foot would be for a 420 square foot addition to a cottage. I want the addition to be built on concrete piers (this is how the existing is built), not a full finished basement.

For the most part, I only want the addition to be a framed "shell". However, the exceptions to this is that I would want the roofing fully completed and the bathroom plumbing roughed in. Also, I would want 3 basic windows installed and an exterior door.

If it makes any difference, about 130 square feet of the above addition is a screened porch. The remainder would be a bathroom, bedroom and hallway (all completely unfinished).

There is full road access to the cottage.

Thank you for your time. It is appreciated.

Kyle